• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.129-137
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• 2013

A force calibration of a nanoindenter and a 3D morphology observation of indenters were carried out in this study. A microbalance calibrated with standard weights was used for measuring the loads generated by a nanoindenter. The indentation load could be calibrated from the ratio of measured and generated loads and the first contact load also could be detected from the microbalance data. By analyzing atomic force microscopy images of two indenters, curvature radii of apexes were determined by $19.71{\pm}3.03$ and $1043.94{\pm}50.91$ nm, respectively, for the nearly new indenter A and the severly worn indenter B. Corresponding bluntness depths were estimated by 1.22 and 64.56 nm for the both indenters by overlapping their profiles on the perfect pyramidal shape. In addition, nanoindentation curves obtained from a fused silica reference material with the both indenters showed a depth difference corresponding to the bluntness depth difference along the indentation depth axis. By shifting amounts of the bluntness depths along the horizontal axis, whole nanoindentation curves overlapped on themselves and resulted in nanohardness values consistent within 1.11 % without considering the complex indenter area function of each indenter.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.193-197
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• 2013

In this study, ultrasonic nonlinear characteristics in the heat-treated aluminum alloy have been evaluated. The nonlinearity of ultrasonic wave has been measured as the acoustic nonlinear parameter ${\beta}$, depending upon the amplitude ratio of the second-order harmonic and the fundamental frequency component of ultrasonic wave propagating through the materials. The parameter ${\beta}$ measurement has been carried out with the reflected signals from the back-wall of specimens at the same plane using the contact-type transducers. The heat-treatment, aging, has been achieved at $300^{\circ}C$ for various durations in the range of 1 to 50 hours. The tensile strength and elongation are obtained by the tensile test and then compared with the parameter ${\beta}$. There is a peak of the acoustic nonlinear parameter ${\beta}$ on 5 hours aging and the ${\beta}$ decreases thereafter, exhibiting closed relations with tensile strength and elongation. Also, the heat-treatment time showing peak in the parameter ${\beta}$ was identical to that showing severe change in the ${\sigma}-{\varepsilon}$ curve. These results suggest that the acoustic nonlinear parameter ${\beta}$ can be used for monitoring the strength variations with aging of aluminum alloys.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.23 no.4
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• pp.391-414
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• 2012

Despite the growth in public concern about health information, the ratio of users who can search for accurate and reliable health information sources has been found to be quite low. Public libraries, as the best contact point to general users, must provide training programs for improving health literacy so that users will have the ability to search and analyze health information, judge the accuracy and reliability of resources, and make informed health-related decisions. This study developed a health information literacy education program suitable for Korean public library users. The effectiveness of the training was measured after administering the program, and necessary improvements were identified. As a result, this study found the education program had the following effects: improved public library users' familiarity with CHI-related terms, improved users' ability to find CHI-related information resources on the Internet, and significantly improved knowledge about health-related websites and information sources. In addition, users expressed interest in seminars on a variety of health information sources in the public library and asked that CHI-related education be included in the library's regular programming. However, this research represented the first time CHI-related education for public library users was performed in Korea, and therefore many limitations were present in the education instructor, the diversity of subjects, and the methodology. Development of more advanced CHI-related education programs for users is still required.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.1-5
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• 2003

In this project, the efficiency of localized heating for micro systems packaging is developed by using a forced potential scheme microheater. Less than 0.2 Mpa contact pressure was used for bonding with a 200 mA current input for $50{\mu}m$ width, $2{\mu}m$ height and $8mm{\times}8mm$, $5mm{\times}5mm$, $3mm{\times}3mm$ sized phosphorus-doped poly-silicon microheater. The temperature can be raised at the bonding region to $800^{\circ}C$, and it was enough to achieve a strong and reliable bonding in 3 minutes. The IR camera test results show improved uniformity in heat distribution compared with conventional microheaters. For performing the gross leak check, IPA (Isopropanol Alcohol) was used. Since IPA has better wetability than water, it can easily penetrate small openings, and is more suitable for conducting a gross leak check. The pass ratio of bonded dies was 67%, for conventional localized heating, and 85% for our newly developed FP scheme. The bonding strength was more than 25Mpa for FP scheme packaging, which shows that FP scheme can be a good candidate for micro-scale hermetic packaging.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.41-51
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• 2004

Recycled plastic containers, so-called 'Tarai' in Korea which are often used as food containers, were collected from 23 domestic manufacturers. Then, their components were analyzed to find out whether they are safe for the use of food-contact material, to meet the standards and specifications of Korean hygienic regulations, the 'Food Code.' The components of the material were analyzed by using Fourier Transform-Infrared (FT-IR), Differential Scanning Calorimeter (DSC), and Elementary Analyzer (EA). The analysis of the FT-IR and the DSC showed that the main component of the samples was polyethylene. Furthermore, the analysis of the EA for 'Tarai' sample revealed the same ratio of C and H elements as in the case of polyethylene which was 1 to 2. Phenol and formaldehyde were not detected in all the samples. As for the antioxidant tests, Irganox 1010, Irganox 1076 and Irganox 1330 were detected in various samples. With regard to the material test for heavy metals, 7 out of 23 samples exceeded the limit value of 100 mg/kg in lead contents. No standard and specification is yet prescribed in the 'Food Code' for the material of 'Tarai' as plastic containers for food. This study suggests that the use of 'Tarai' as a food container should be strictly controlled.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.9-14
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• 2020

Four developed patents have applied for a new type of Composite Cyclone Scrubber followed by the previous research (Cho and Kim, 2017), including dust reducing fan with filters. Regarding target installation and maintenance cost, 64% reduction for investment costs (6.2 billion won vs. 17 billion won) compared to existing road pollution reduction system, while social benefit costs increase by 43% compared to existing road pollution reduction measures (72.6 billion won vs. 50.8 billion won). The composition of the device is an air blower type spiral guide vane, and an injection pressure collecting dust efficiency. A nozzle varies Injection angle and contact range, spray liquid species (waterworks, salty water). The proposed patent tests are circulation water Time-by-Time Spray and collected 41.4% more increased micro dust since the sprayed water meets contaminated gas due to the 45° degree colliding, which is 141% increased conventional dust collector. (Ratio of collection over 85%). As regards the source of collection liquid, circulated rainwater and well water, we expect a huge amount of energy and economically saved eco-friendly system in our patent. Finally, the guided vane and metal filter reduced over 90% micro-dust, while sprayed water cleans the vane and filters, resultantly minimizing the maintenance budget. The preliminary evaluations of the developed design make it possible to reduce not only cheaper maintenance budget due to the characteristic water spraying but the cost of water comes from mainly rain and underground.

• Journal of the Korean Geosynthetics Society
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• v.16 no.1
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• pp.31-39
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• 2017

The fundamental study for an application of nanobubble as a soil remediation enhancer on heavy metal contaminated soil was carried out. The existence and long-term stability of hydrogen nanobubbles were investigated by particle analysis and zeta-potential analysis. And the removal efficiency of copper using nanobubble water(NBW) and distilled water(DW) were compared and analyzed through a batch desorption test. As a result, it is confirmed that nanobubble which was fabricated by compression-dissolution type generator can exist for more than 14 days. The results of batch test show that copper removal of NBW was higher than that of DW irrespectively to soil type and increased as solid-liquid ratio and contact time increased, respectively. According to the pH change, the removal of copper on sand was higher on the acid side but the removal difference was slightly lower on the clay. It is considered that a high efficiency of NBW in copper removal is due to the large surface area and high zeta-potential of nanobubbles. Therefore, the nanobubble can be applied to soil remediation for heavy-metal contaminated soil as an eco-friendly enhancer.

• Journal of Korean society of Dental Hygiene
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• v.9 no.3
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• pp.468-478
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• 2009

This research was performed to provide basic data for the development of infection related dental hygiene studies by surveying the current condition of recognition among students in the department of dental hygiene toward hospital infection management while receiving the following results by using a personal self-administered survey method targeting 303 students in the department of dental hygiene from certain areas. 1. With the current condition of recognition on the sanitization and sterilization of instruments among students in the department of dental hygiene(study), the rate at which surgical instruments are to be sterilized with autoclaves was 79.9% which was relatively higher than other instruments while it was shown that prosthetic instruments for treatment was 56.4%, conservative instruments for treatment was 51.8%, and ultrasonic scaler tip was 51.1% while the way syringe tips(36.1%) and the dental anesthetic apparatus(27.9%) were revealed to require sanitization by alcohol. 2. The 'hand wash' area was the highest with 4.71 while the 'materials and environment management' area and 'equipment management' area appeared high respectively with 4.43 and 4.41. 3. With the current condition of recognition on equipment management, 'equipments used for contagious patients are separately washed after a one-time use and must be sterilized or separated-and-discarded' was the highest with 4.82 while 'sterilization equipments with humidity or water on it are considered contaminated and are not used' showed the lowest recognition level with 3.90. 4. Regarding the current condition of materials and environment management, 'contagious and general trash are separated and discarded' was the highest with 4.70 while 'the refrigerator for medicine storage is cleaned on a regular basis once a month' was revealed as the lowest with 4.11. 5. With the current condition of recognition on hand washing, 'one must wash their hands after coming in contact with contagious patients, was the highest with 4.90 while washing hands after taking off gloves' appeared as the lowest with 4.51 point. To conclude department of dental hygiene there is to infection management and necessary about organization disinfecting and pasteurization to strengthen an education in order raising a stamp helping practical ratio about the infection management which whole, is from presence at a sickbed and connection does and about the infection management which is substantial and educational program development leads feed with the fact that deepening studying which is continuous must become accomplished becomes.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.365-372
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• 1993

$CO_2$ methanation was performed over Ni supported on cation-exchanged Y zeolites under atmospheric pressure at $250{\sim}550^{\circ}C$ and $H_2/CO_2$ mole ratio of 4. Adsorption strength between carbon dioxide and nickel was found to be Influenced by the cation exchanged in the zeolite. TPD(Temperature-programmed desorption) results show that the adsorption strength decreases in the order of Ni/NaY>Ni/MaY>Ni/HY. TPSR(Temperature-programmed surface reaction) results indicate that enhanced methanation activity is obtained when the adsorption strength between carbon dioxide and nickel is stroing. As the reduction temperature increases, the methantion activity of the catalyst increase. From this result the larger size nickel particle seems advantageous for $CO_2$ methanation reaction. The maximum activity is obtained when nickel loading is 3.3wt%. Carbon monoxide is produced as a by-product throughout the reaction temperature range, and as the contact time increases, the selectivity to methane increases and the selectivity to carbon monoxide decreases steadily. Thus methane seems to be produced from $CO_2$ via CO as an intermediate species. In the temperature range of $410{\sim}450^{\circ}C$, the methane production rate is found to be dependent on the orders of 3.3~-0.5 and 1.4~3.6 with respect to $CO_2$ and $H_2$ partial pressures, respectively. This clearly shows that $CO_2$ and $H_2$ are competing for adsorption sites and as the reaction temperature increases, it becomes increasingly difficult for $H_2$ to be adsorbed on the catalyst surface.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.142-146
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• 2014

The separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction of nine components system was investigated by distribution equilibrium. The model coal tar fraction comprising NHC group (NHCs; indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine(Qu)), bicyclic aromatic compound group (BACs; 1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN)), biphenyl (Bp) and phenyl ether (Pe) and the aqueous methanol were used as the raw materials and the solvent of this work, respectively. A batch-stirred tank was used as the liquid-liquid contact unit of this work. The distribution coefficient of NHCs increased by increasing the equilibrium operation temperature, whereas the selectivity of NHCs with respect to BACs decreased. Decreasing the initial volume ratio of water to the solvent resulted in deteriorating the selectivity of NHCs in reference to BACs, but improving the distribution coefficients of NHCs. At a fixed experimental condition, the sequence of the distribution coefficient and the selectivity with reference to BACs for each groups was increased in order of NHCs > Bp > BACs > Pe and NHCs > Bp> Pe, respectively. Also, the sequence of the distribution coefficient for entire compounds was in order of In > iQ = Q > Qu > Bp > 1MN = 2MN > Pe > DMN. The maximum yield of NHCs and the selectivity of NHCs based on BACs obtained by methanol extraction were 94 and 23%, respectively. Furthermore, the recovery process for NHCs from coal tar was studied by using the experimental results from this work.